US 11,899,237 B2
Multicore optical fiber, method of designing multicore optical fiber, and optical transmission method
Takashi Matsui, Musashino (JP); and Kazuhide Nakajima, Musashino (JP)
Assigned to Nippon Telegraph and Telephone Corporation, Tokyo (JP)
Appl. No. 17/294,892
Filed by Nippon Telegraph and Telephone Corporation, Tokyo (JP)
PCT Filed Nov. 8, 2019, PCT No. PCT/JP2019/043826
§ 371(c)(1), (2) Date May 18, 2021,
PCT Pub. No. WO2020/105470, PCT Pub. Date May 28, 2020.
Claims priority of application No. 2018-218153 (JP), filed on Nov. 21, 2018.
Prior Publication US 2022/0003920 A1, Jan. 6, 2022
Int. Cl. G02B 6/02 (2006.01); G02B 27/00 (2006.01)
CPC G02B 6/02042 (2013.01) [G02B 27/0012 (2013.01)] 9 Claims
OG exemplary drawing
 
1. A multicore optical fiber comprising:
four cores having a radius a1 disposed in a longitudinal direction in square lattice shape;
first cladding regions disposed around each of the cores and having a radius a2 with a refractive index lower than a refractive index of the cores, a specific relative refractive index difference to the cores being Δ1; and
a second cladding region disposed on an outer periphery of the first cladding regions and having a refractive index higher than the refractive index of the first cladding regions and lower than the refractive index of the cores, a specific relative refractive index difference to the core being Δ2, wherein
an outer diameter of the second cladding region is 125±1 μm,
an effective cross-sectional area at a wavelength of 1550 nm is 80 μm2 or more,
bending loss at a wavelength of 1625 nm and a bending radius of 30 mm is 0.1 dB/100 turns or less, and
a cutoff wavelength is 1530 nm or less.